Rail hold down system



Dec. 2, 1969 F. K. HALL RAIL HOLD DOWN SYSTEM Filed Feb. 23. 1968 INVE/VTOR.

FRANK KENNETH HALL I mifiw EH1- 5 United States Patent RAIL HOLD DOWN SYSTEM Frank Kenneth Hall, Findlay, Ohio, assignor to The D. S.

Brown Company, North Baltimore, Ohio, 21 corporation of Ohio Filed Feb. 23, 1968, Ser. No. 707,850 Int. Cl. E01b 9/28, 9/38 U.S. Cl. 238349 12 Claims ABSTRACT OF THE DISCLOSURE Rail hold down system embodying hold down assembly with resiliently biased hold down members pressing against upper face of base flange of railroad rail; resilient bias preferably is compressed elastomer body positioned between hold down member and cross plate extending between pair of fixed inverted U-bars projecting upwardly from upper face of underlying rail support structure.

Background of the invention and related applications The present invention concerns hold down systems particularly adapted to securely position a railroad rail on a support member or underlying structure. The invention particularly concerns the hold down systems adapted for use with concrete ties, concrete beds, metal superstructures, and like support structures. It further pertains to other uses wherein one member is to be held in position relative to another member and may be used in lieu of bolt connections, welded connections, etc.

Railroad rails traditionally have been mounted on wooden cross ties spaced at close intervals by the driving of railroad spikes into the ties with the head portion of the spike overlapping the base flange of the rail. This has been true of below ground and on ground rail systems and above ground, or elevated, rail systems. With the fairly recent advent of improvements in the structural strength of concrete, rail systems embodying concrete ties or concrete beds have awakened the interest of railroad designers. Concrete beds or ties require considerable less maintenance and have a longer useful life than do the traditional wooden ties.

The adaptation of rail systems to the use of concrete ties and concrete road beds, however, also require a departure from the traditional concept of holding the rail on the ties, i.e., by spikes being driven into the wooden ties. Hold down systems for rails on concerte ties and/or concrete road beds or metal superstructures have been developed in recent years. Known hold down systems embody heavy metal structures. Some utilize metal components in torsion stress as the force-exerting members. A specific object of the present invention concerns improvements in rail hold down systems wherein the traditional, wooden ties concept is abandoned in favor of pre-stressed concrete ties, metal superstructures and/ or concrete road beds in below ground, on ground or elevated rail systems.

Brief summary of the invention Briefly, the invention concerns holding systems in general, i.e., systems for holding one member relative to another comprsing a first member, a second member contiguous thereto to be held in fixed position relative to said first member, and means for transmitting thrust between said members including a compressively deformed bias member, preferably a solid elastomer body having 0pposite substantially parallel faces exerting an outward elastic recovery thrust against substantially parallel faces with lines of thrust forces in said compressively deformed member being essentially at right angles to said faces. An exemplary use thereof comprises rail hold down systems wherein the railroad rails are secured by a series of hold 3,481,539 Patented Dec. 2, 1969 down devices materially different from and considerably improved over the traditional railroad spike. The hold down systems herein and in any below-listed, related applications embody a hold down member, e.g., a hold down or pressure plate pressed downwardly against the upper face of the base flange. The pressure exerted thereby is of a relatively high magnitude, i.e., in the order of at least several hundred p.s.i. and a total force of at least two thousand pounds. This pressure is provided by a resilient bias member, preferably elastomer pressure body, positioned between a fixed inverted U-member and the hold down member. The elastomer body is distorted compressively from its normal, unstressed state whereby the elastic recovery thrust forces resulting from the compressive distortion exerts a pressure thrust force of relatively high magnitude, suflicient to secure the rail tightly on ties or other rail support members.

The elastomer pressure member is inserted in the hold down system on the construction site. As is well known, it is difficult to insert an elastomer member in a highly compressed state. To facilitate such insertion, the elastomer member may be compressively distorted or flattened, whereafter its temperature is lowered sufliciently to immobilize or freeze the member in the compressed or flattened state when the compression force is removed. It is maintained at this temperature until it is inserted on the job in the hold down system. Upon thawing or warming, the elastomer body regains its elastic recovery property and recovers toward its normal shape, which is the shape of the elastomer member before compressive distortion and low temperature immobilization thereof. The hold down system is dimensioned so that the inserted elastomer member cannot recover fully its original or normal shape, whereby the elastomer member is in a partially compressed state when it exerts its thrust force against the hold down member. Thereby, there exists in effect the elastomer member in a partially compressed state. Through the utilization of the elastic recovery force of said member in attempting to return it to its original or normal state, it functions as the pressure exerting body in the hold down system.

The elastomer member may also be compressed between opposing, preferably substantially parallel faces of a hold down system or the like by other means. For example, the elastomer member may be inserted in an uncompressed state, and one or more shims may be driven between the body and the contiguous face of the hold down member to compress the elastomer member. Alternatively, the hold down device may be made in separate parts and assembled on the job site in a manner whereby the elastomer member is compressed upon assembly.

This invention concerns improvements in hold down systems of the type above described and more particularly disclosed in my copending application filed on or about Feb. 7, 1968, and my copending application filed of approximately even date herewith.

Improvements herein The improvements herein reside in hold down unit structures wherein a pair of fixed, spaced, inverted U-bars having major planes substantially at right angles to the longitudinal axis of a railroad rail project upwardly from the underlying, rail-support structure, e.g., a concrete cross tie or concrete bed or metal superstructure, contiguous to a longitudinal edge of the base flange of the rail. A cross plate extends between said U-bars adjacent the upper cross bar thereof. The cross plate may have two notches in each longitudinal edge and preferably is removably mounted between said inverted U-bars with the upwardly projecting side legs of said inverted U-bars positioned in respective notches. The inverted U-bars may be tilted away from the rail to slope the under face of the cross plate for a purpose later described or may be vertical.

A hold down member, e.g., a pressure plate, extends between said inverted U-bars beneath said cross plate with the inner portion of the underside thereof seated on the upper face of the base flange. The pressure plate may have a flat undersurface substantially flatly pressed against the upper face of the base flange. When the upper face of said flange is sloped, the pressure plate preferably is sloping with said undersurface substantially parallel with the upper face.

A compressively distorted, resilient bias member is provided between the cross plate and hold down member (pressure plate) and presses, via its elastic recovery thrust, the underside of the latter against said base flange. The resilient bias member preferably is a compressively distorted, solid elastomer body, e.g., a rectangular parallelepiped. The lower face of the cross plate slopes whereby it is substantially parallel with the opposed upper face of the sloping hold down member to provide substantially parallel, thrust bearing surfaces. The pressure plate preferably is a substantially flat plate and may have a downwardly depending, elongated flange on the outer edge thereof. The flange is seated in an elongated seat on the upper face of the tie or other underlying rail-support structure to position the pressure plate, to prevent its working outward, and to provide a pivot fulcrum for the pressure plate.

Description of drawings A preferred embodiment of the subject invention is illustrated in the drawings wherein:

FIGURE 1 is an end elevation of an embodiment of a rail hold down system with the railroad rail shown in cross section and the underlying concrete tie shown in fragment;

FIGURE 2 is a top plan view thereof with the rail and tie shown in fragment;

FIGURE 3 is a side elevation thereof with the rail and tie shown in fragment;

FIGURE 4 is a top plan view of the cross bar.

Description of preferred embodiment The rail hold down assembly is mounted on rail-support structure, which may be a series of railroad cross ties, an elevated, on ground or below ground concrete railroad bed, or a series of cross structures such as steel structural members of an elevated monorail or dual rail system. The ties or railroad bed may be of any suitable material, but generally will be concrete. The rail has the usual base flange 11, the upper surface 12 of which generally slopes outwardly but may be at right angles to the vertical axis of the rail if desired. In the illustrated embodiment the rail hold down system is mounted on the upper face of a concrete tie 13. The rail hold down system comprises at least one, preferably two, opposing, hold down assemblies or units 15 and 16, one on each side of the base flange 11. Each assembly or unit 15 and 16 comprises a pair of spaced, inverted U-bars 17 and 18 having their planes substantially at right angles to the longitudinal axis of the rail. Each inverted U-bar comprises outwardly and upwardly extending side legs 19 and 20 connected at their upper ends by a diagonally-oriented cross bar 21. The lower portions 22 of the side legs are embedded in the concrete and have outturned ends 23 to secure the legs in the concrete against displacement in said concrete.

A cross plate 25 extends between respective pairs of inverted U-bars 17 and 18 and has two notches 26 in each longitudinal side. The legs 19 and 20 are seated in these notches to prevent accidental displacement of the cross plates from the assembly. The cross plates 25 are removable, however. A segment 25a projects inwardly beyond contiguous notches 26 and legs 20 to allow resilient bias members 32 to be positioned immediately next to or even partially over upper faces 12, thereby better utilizing the mechanical advan age inherent in he hir c ss lever system of hold down members or plates 27, hereafter described, in terms of downward thrust pressure transmittal from bias members 32 against base flange 11.

A hold down member comprising a substantially flat pressure plate 27 extends diagonally upwardly from tie 13 between inverted U-bars 17 and 18 and under cross bar 25. The substantially planar undersurface 28 of its inner portion presses substantially flatly against the upper face 12 of base flange 11.

An elongated seat, as aforedescribed, on the upper face of cross tie 13 is provided by the grooves 30 therein. These grooves are contiguous to outer side legs 19 and form a retaining seat and fulcrum for the downwardly depending flanges or tongues 31 extending along the outer edges of each pressure plate 27.

The resilient bias member which thrusts plate 27 tightly against base flange 11 is a solid, elastomer body or block 32. It preferably has flat, parallel upper and lower faces which thrust against the substantially parallel, opposing lower face of cross plate 25 and upper face of pressure plate 27. If desired, an elastomer pad 33 may be interposed between base flange 11 and cross tie 13.

Prior to inserting the elastomer blocks or bodies, they usually are distorted by compression into a flattened form, with a dimension slightly less than the spaces be tween cross plate 25 and hold down members 27. They are inserted in the distorted or compressed shape and thereafter allowed to recover via the elastic forces of the elastomer block or body toward its normal state, i.e., the shape it would assume without any compressive forces exerted thereon. In this elastic recovery, the elastomer bodies press against these hold down members and thus exert a downward thrust thereon. This force is in turn transmitted against the upper face 12 of the base flange 11 to hold the rail securely in position.

The aforesaid opposing faces of the cross plate 25 and respective hold down members 27 are preferably substantially parallel, planar faces for achieving maximum effect of the thrust forces of the resilient bias members 32. The latter, in turn, are generally rectangular parallelepipeds in the relaxed (undistorted) state having a height or thickness considerably greater than the distance between said opposing faces. A notched gauge bar 33 with legs 20 in its notches functions as a spacer between a longitudinal edge of base flange 11 and the fixed member 37 to hold rail 10 against lateral sliding under lateral thrust such as exerted by railway wheels against the outer rail in a curved section of track.

As aforesaid, it normally would be diflicult to insert the compressively distorted, elastomer bodies between said faces. To facilitate such insertion, it is preferred that the elastomer bodies be compressively distorted in a flattened shape and frozen or immobilized in this state. They are held at the freezing or low temperature immobilization until inserted. As the elastomer bodies warm their resilient properties are restored and they seek to resume their shape prior to compressive distortion and freezing. In so doing, they become wedged between said faces and thus exert a downward thrust on the hold down members.

The terms freezing and thawing above, are nontechnical descriptions. In practice, the elastomer bodies are formulated so that the elastomer composition will rigidify, through loss of certain elastic properties, at relatively low temperatures, i.e., in the order of 40 F. and below. The elastomers also should have good resistance to atmospheric deterioration in the presence of sunlight, atmospheric oxygen, and ozone, and should retain their elastic properties also at relatively high temperatures on the order of to F. The elastomer compositions useful for this purpose may be formulated from elastomers which crystallize at relatively low tem-. peratures with the loss of elastic properties upon crystala lization. Exemplary thereof are low crystallization neo.

prene elast'omers. However, elastomers which are usually considered to be noncrystalline elastomers, e.g., natural rubber and most synthetic rubbers, can be immobilized or rigidified in the compressively distorted state at low temperatures in the order of 0 F. to -l00 F. or even lower. The invention herein contemplates use of any natural or synthetic rubber composition wherein such low temperature immobilization can be attained. The selection of a particular elastomer composition will depend in part on the climate of the locale where the installation is made. In northern parts of the temperate zone, a low temperature immobilization of -30 F. or below is recommended. In the arctic zone, a low temperature immobilization of 60 F. or below is recommended,

whereas in southern parts of the temperate zone and in the tropical zone 0 F. or below would be suitable. In each instance, the low temperature immobilization is selected so that is will not be reached and preferably not even closely approached under the coldest climate conditions of the particular locale.

Thus, in its broader concepts the invention herein provides a system for holding one member relative to another by a compressively distorted, resilient bias member, preferably a solid elastomer body or block. The system embodies a first member and a second member to be held in fixed position relative to the first member. The system embodies substantially parallel, opposed faces against which the compressively distorted elastomer body is positioned with its opposite faces pressing against said opposed faces to give an elastic recovery thrust force urging said faces apart along lines of thrust force at right angles to said faces. This combination utilizes the elastic recovery forces in the compressed elastomer body more effectively than would be the case if the elastomer body were subject to twisting. In the latter case, the torque elastic recovery forces in the twisted elastomer adopt a sine cure-like configuration. Such recovery forces are considerably less effective in terms of amount of elastic recovery thrust forces per unit of distortion or deformation of the elastomer body as compared against the thrust force orientation achieved by this invention.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. In a railroad system embodying a rail having a base flange supported on an underlying structure, the improvement of a hold down unit comprising a pair of inverted U-bars having respective side legs aflixed to said structure and projecting upwardly therefrom and a connecting cross bar spaced above said structure, said inverted U-bars being contiguous to a longitudinal edge of said base flange and having their planes substantially at right angles thereto, a cross plate extending between said inverted U-bars adjacent said cross bars, a hold down member extending beneath said cross plate with the inner portion of the underside thereof seated on the upper surface of said base flange, and a compressively distorted, resilient bias member between said cross plate and hold down member pressing said inner portion of said underside against said upper surface of said base flange.

2. An improvement as claimed in claim 1, wherein said bias member is a compressively distorted body of solid elastomer.

3. An improvement as claimed in claim 1, wherein said underlying structure comprises concrete and the lower edges of said side legs are fixedly embedded in said concrete.

4. An improvement as claimed in claim 1, wherein said cross plate has two notches in each longitudinal edge, and said cross plate being removably mounted between said inverted U-bars with said side legs thereof positioned in respective notches.

5. An improvement as claimed in claim 1, wherein said hold down member comprises a pressure plate having a substantially fiat undersurface with the inner portion thereof lying substantially flatly on said upper surface of said base flange.

6. An improvement as claimed in claim 5, wherein the outer edge of said plate rests on said underlying structure.

7. An improvement as claimed in claim 5, wherein said pressure plate comprises a substantially flat plate having a downwardly depending elongated flange along the outer edge thereof, means forming a groove in said underlying structure, and said flange being seated in said groove.

8. The improvement wherein the rail hold down system comprises two, opposing hold down units as claimed in claim 1, said units being disposed at opposite sides of said base flange.

9. The improvement wherein the rail hold down system comprises two, opposing hold down units as claimed in claim 2, said units being disposed at opposite sides of said base flange.

10. The improvement wherein the rail hold down system comprises two, opposing hold down units as claimed in claim 4, said units being disposed at opposite sides of said base flange.

11. The improvement wherein the rail hold down system comprises two, opposing hold down units as claimed in claim 5, said units being disposed at opposite sides of said base flange.

12. The improvement wherein the rail hold down system comprises two, opposing hold down units as claimed in claim 7, said units being disposed at opposite sides of said base flange.

References Cited UNITED STATES PATENTS 2,162,599 6/1939 Austin et al. 2,252,515 8/ 1941 Landis. 2,257,923 10/ 1941 Verplanck. 2,377,942 6/1945 Johnson. 2,779,543 1/ 1957 Gronlund.

ARTHUR L. LAPOINT, Primary Examiner RICHARD A. BERTSCH, Assistant Examiner 

